18720533329 has 9 divisors (see below), whose sum is σ = 19040947419. Its totient is φ = 18405429960.

The previous prime is 18720533327. The next prime is 18720533371. The reversal of 18720533329 is 92333502781.

The square root of 18720533329 is 136823.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 608756929 + 18111776400 = 24673^2 + 134580^2 .

It is not a de Polignac number, because 18720533329 - 2¹ = 18720533327 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18720533327) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 8345082 + ... + 8347324.

Almost surely, 2^18720533329 is an apocalyptic number.

18720533329 is the 136823-rd square number.

18720533329 is the 68412-nd centered octagonal number.

It is an amenable number.

18720533329 is a deficient number, since it is larger than the sum of its proper divisors (320414090).

18720533329 is an frugal number, since it uses more digits than its factorization.

18720533329 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4608 (or 2304 counting only the distinct ones).

The product of its (nonzero) digits is 272160, while the sum is 43.

It can be divided in two parts, 18720 and 533329, that added together give a square (552049 = 743²).

The spelling of 18720533329 in words is "eighteen billion, seven hundred twenty million, five hundred thirty-three thousand, three hundred twenty-nine".